2 .\" Mach Operating System
3 .\" Copyright (c) 1991,1990 Carnegie Mellon University
4 .\" Copyright (c) 2007 Robert N. M. Watson
5 .\" All Rights Reserved.
7 .\" Permission to use, copy, modify and distribute this software and its
8 .\" documentation is hereby granted, provided that both the copyright
9 .\" notice and this permission notice appear in all copies of the
10 .\" software, derivative works or modified versions, and any portions
11 .\" thereof, and that both notices appear in supporting documentation.
13 .\" CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
14 .\" CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
15 .\" ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
17 .\" Carnegie Mellon requests users of this software to return to
19 .\" Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
20 .\" School of Computer Science
21 .\" Carnegie Mellon University
22 .\" Pittsburgh PA 15213-3890
24 .\" any improvements or extensions that they make and grant Carnegie Mellon
25 .\" the rights to redistribute these changes.
27 .\" changed a \# to #, since groff choked on it.
31 .\" Revision 1.1 1993/07/15 18:41:02 brezak
34 .\" Revision 2.6 92/04/08 08:52:57 rpd
36 .\" [92/01/17 14:19:22 jsb]
37 .\" Changes for OSF debugger modifications.
40 .\" Revision 2.5 91/06/25 13:50:22 rpd
41 .\" Added some watchpoint explanation.
44 .\" Revision 2.4 91/06/17 15:47:31 jsb
45 .\" Added documentation for continue/c, match, search, and watchpoints.
46 .\" I've not actually explained what a watchpoint is; maybe Rich can
47 .\" do that (hint, hint).
48 .\" [91/06/17 10:58:08 jsb]
50 .\" Revision 2.3 91/05/14 17:04:23 mrt
51 .\" Correcting copyright
53 .\" Revision 2.2 91/02/14 14:10:06 mrt
54 .\" Changed to new Mach copyright
55 .\" [91/02/12 18:10:12 mrt]
57 .\" Revision 2.2 90/08/30 14:23:15 dbg
68 .Nd interactive kernel debugger
70 In order to enable kernel debugging facilities include:
71 .Bd -ragged -offset indent
76 To prevent activation of the debugger on kernel
78 .Bd -ragged -offset indent
79 .Cd options KDB_UNATTENDED
82 In order to print a stack trace of the current thread on the console
84 .Bd -ragged -offset indent
88 To print the numerical value of symbols in addition to the symbolic
89 representation, define:
90 .Bd -ragged -offset indent
91 .Cd options DDB_NUMSYM
96 backend, so that remote debugging with
99 .Bd -ragged -offset indent
105 kernel debugger is an interactive debugger with a syntax inspired by
107 If linked into the running kernel,
108 it can be invoked locally with the
112 The debugger is also invoked on kernel
115 .Va debug.debugger_on_panic
117 MIB variable is set non-zero,
123 The current location is called
128 a hexadecimal format at a prompt.
135 to the address of the last line
136 examined or the last location modified, and set
139 the next location to be examined or changed.
140 Other commands do not change
147 The general command syntax is:
148 .Ar command Ns Op Li / Ns Ar modifier
149 .Ar address Ns Op Li , Ns Ar count
151 A blank line repeats the previous command from the address
154 count 1 and no modifiers.
167 to be 1 for printing commands or infinity for stack traces.
171 debugger has a pager feature (like the
175 If an output line exceeds the number set in the
177 variable, it displays
179 and waits for a response.
180 The valid responses for it are:
182 .Bl -tag -compact -width ".Li SPC"
188 abort the current command, and return to the command input mode
193 provides a small (currently 10 items) command history, and offers
196 command line editing capabilities.
200 control keys, the usual
202 arrow keys may be used to
203 browse through the history buffer, and move the cursor within the
206 .Bl -tag -width indent -compact
209 Display the addressed locations according to the formats in the modifier.
210 Multiple modifier formats display multiple locations.
211 If no format is specified, the last format specified for this command
214 The format characters are:
215 .Bl -tag -compact -width indent
217 look at by bytes (8 bits)
219 look at by half words (16 bits)
221 look at by long words (32 bits)
223 look at by quad words (64 bits)
225 print the location being displayed
227 print the location with a line number if possible
229 display in unsigned hex
231 display in signed hex
233 display in unsigned octal
235 display in signed decimal
237 display in unsigned decimal
239 display in current radix, signed
241 display low 8 bits as a character.
242 Non-printing characters are displayed as an octal escape code (e.g.,
245 display the null-terminated string at the location.
246 Non-printing characters are displayed as octal escapes.
248 display in unsigned hex with character dump at the end of each line.
249 The location is also displayed in hex at the beginning of each line.
251 display as an instruction
253 display as an instruction with possible alternate formats depending on the
255 .Bl -tag -width ".Tn powerpc" -compact
268 display a symbol name for the pointer stored at the address
275 command with the last specified parameters to it
276 except that the next address displayed by it is used as the start address.
282 command with the last specified parameters to it
283 except that the last start address subtracted by the size displayed by it
284 is used as the start address.
286 .It Ic print Ns Op Li / Ns Cm acdoruxz
287 .It Ic p Ns Op Li / Ns Cm acdoruxz
290 according to the modifier character (as described above for
293 .Cm a , x , z , o , d , u , r ,
296 If no modifier is specified, the last one specified to it is used.
299 can be a string, in which case it is printed as it is.
301 .Bd -literal -offset indent
302 print/x "eax = " $eax "\enecx = " $ecx "\en"
306 .Bd -literal -offset indent
312 .Ic write Ns Op Li / Ns Cm bhl
313 .Ar addr expr1 Op Ar expr2 ...
316 .Ic w Ns Op Li / Ns Cm bhl
317 .Ar addr expr1 Op Ar expr2 ...
319 Write the expressions specified after
321 on the command line at succeeding locations starting with
323 The write unit size can be specified in the modifier with a letter
329 (long word) respectively.
331 long word is assumed.
334 since there is no delimiter between expressions, strange
336 It is best to enclose each expression in parentheses.
338 .It Ic set Li $ Ns Ar variable Oo Li = Oc Ar expr
339 Set the named variable or register with the value of
341 Valid variable names are described below.
343 .It Ic break Ns Op Li / Ns Cm u
344 .It Ic b Ns Op Li / Ns Cm u
349 is supplied, continues
351 \- 1 times before stopping at the
353 If the break point is set, a break point number is
356 This number can be used in deleting the break point
357 or adding conditions to it.
361 modifier is specified, this command sets a break point in user
365 option, the address is considered to be in the kernel
366 space, and a wrong space address is rejected with an error message.
367 This modifier can be used only if it is supported by machine dependent
371 If a user text is shadowed by a normal user space debugger,
372 user space break points may not work correctly.
374 point at the low-level code paths may also cause strange behavior.
376 .It Ic delete Ar addr
378 .It Ic delete Li # Ns Ar number
379 .It Ic d Li # Ns Ar number
380 Delete the break point.
381 The target break point can be specified by a
382 break point number with
386 specified in the original
390 .It Ic watch Ar addr Ns Li , Ns Ar size
391 Set a watchpoint for a region.
392 Execution stops when an attempt to modify the region occurs.
395 argument defaults to 4.
396 If you specify a wrong space address, the request is rejected
397 with an error message.
400 Attempts to watch wired kernel memory
401 may cause unrecoverable error in some systems such as i386.
402 Watchpoints on user addresses work best.
404 .It Ic hwatch Ar addr Ns Li , Ns Ar size
405 Set a hardware watchpoint for a region if supported by the
407 Execution stops when an attempt to modify the region occurs.
410 argument defaults to 4.
413 The hardware debug facilities do not have a concept of separate
414 address spaces like the watch command does.
417 for setting watchpoints on kernel address locations only, and avoid
418 its use on user mode address spaces.
420 .It Ic dhwatch Ar addr Ns Li , Ns Ar size
421 Delete specified hardware watchpoint.
423 .It Ic step Ns Op Li / Ns Cm p
424 .It Ic s Ns Op Li / Ns Cm p
427 times (the comma is a mandatory part of the syntax).
430 modifier is specified, print each instruction at each step.
431 Otherwise, only print the last instruction.
434 depending on machine type, it may not be possible to
435 single-step through some low-level code paths or user space code.
436 On machines with software-emulated single-stepping (e.g., pmax),
437 stepping through code executed by interrupt handlers will probably
440 .It Ic continue Ns Op Li / Ns Cm c
441 .It Ic c Ns Op Li / Ns Cm c
442 Continue execution until a breakpoint or watchpoint.
445 modifier is specified, count instructions while executing.
446 Some machines (e.g., pmax) also count loads and stores.
449 when counting, the debugger is really silently single-stepping.
450 This means that single-stepping on low-level code may cause strange
453 .It Ic until Ns Op Li / Ns Cm p
454 Stop at the next call or return instruction.
457 modifier is specified, print the call nesting depth and the
458 cumulative instruction count at each call or return.
460 only print when the matching return is hit.
462 .It Ic next Ns Op Li / Ns Cm p
463 .It Ic match Ns Op Li / Ns Cm p
464 Stop at the matching return instruction.
467 modifier is specified, print the call nesting depth and the
468 cumulative instruction count at each call or return.
469 Otherwise, only print when the matching return is hit.
472 .Ic trace Ns Op Li / Ns Cm u
477 .Ic t Ns Op Li / Ns Cm u
482 .Ic where Ns Op Li / Ns Cm u
487 .Ic bt Ns Op Li / Ns Cm u
494 option traces user space; if omitted,
498 The optional argument
500 is the number of frames to be traced.
503 is omitted, all frames are printed.
506 User space stack trace is valid
507 only if the machine dependent code supports it.
510 .Ic search Ns Op Li / Ns Cm bhl
518 This command might fail in interesting
519 ways if it does not find the searched-for value.
522 does not always recover from touching bad memory.
525 argument limits the search.
532 Prints the thread address for a thread kernel-mode stack of which contains the
534 If the thread is not found, search the thread stack cache and prints the
535 cached stack address.
536 Otherwise, prints nothing.
538 .It Ic show Cm all procs Ns Op Li / Ns Cm a
539 .It Ic ps Ns Op Li / Ns Cm a
540 Display all process information.
541 The process information may not be shown if it is not
542 supported in the machine, or the bottom of the stack of the
543 target process is not in the main memory at that time.
546 modifier will print command line arguments for each process.
549 .It Ic show Cm all trace
552 Show a stack trace for every thread in the system.
554 .It Ic show Cm all ttys
555 Show all TTY's within the system.
558 but also includes the address of the TTY structure.
561 .It Ic show Cm allchains
562 Show the same information like "show lockchain" does, but
563 for every thread in the system.
566 .It Ic show Cm alllocks
567 Show all locks that are currently held.
568 This command is only available if
570 is included in the kernel.
573 .It Ic show Cm allpcpu
574 The same as "show pcpu", but for every CPU present in the system.
577 .It Ic show Cm allrman
578 Show information related with resource management, including
579 interrupt request lines, DMA request lines, I/O ports, I/O memory
580 addresses, and Resource IDs.
584 Dump data about APIC IDT vector mappings.
587 .It Ic show Cm breaks
588 Show breakpoints set with the "break" command.
591 .It Ic show Cm bio Ar addr
592 Show information about the bio structure
600 for more details on the exact meaning of the structure fields.
603 .It Ic show Cm buffer Ar addr
604 Show information about the buf structure
610 header file for more details on the exact meaning of the structure fields.
613 .It Ic show Cm callout Ar addr
614 Show information about the callout structure
620 .It Ic show Cm cbstat
621 Show brief information about the TTY subsystem.
625 Without argument, show the list of all created cdev's, consisting of devfs
626 node name and struct cdev address.
627 When address of cdev is supplied, show some internal devfs state of the cdev.
630 .It Ic show Cm conifhk
631 Lists hooks currently waiting for completion in
632 run_interrupt_driven_config_hooks().
635 .It Ic show Cm cpusets
636 Print numbered root and assigned CPU affinity sets.
642 .It Ic show Cm cyrixreg
643 Show registers specific to the Cyrix processor.
646 .It Ic show Cm domain Ar addr
647 Print protocol domain structure
653 header file for more details on the exact meaning of the structure fields.
656 .It Ic show Cm ffs Op Ar addr
657 Show brief information about ffs mount at the address
659 if argument is given.
660 Otherwise, provides the summary about each ffs mount.
663 .It Ic show Cm file Ar addr
664 Show information about the file structure
671 Show information about every file structure in the system.
674 .It Ic show Cm freepages
675 Show the number of physical pages in each of the free lists.
678 .It Ic show Cm geom Op Ar addr
681 argument is not given, displays the entire GEOM topology.
684 is given, displays details about the given GEOM object (class, geom,
685 provider or consumer).
690 The first column specifies the IDT vector.
691 The second one is the name of the interrupt/trap handler.
692 Those functions are machine dependent.
695 .It Ic show Cm inodedeps Op Ar addr
696 Show brief information about each inodedep structure.
699 is given, only inodedeps belonging to the fs located at the
700 supplied address are shown.
703 .It Ic show Cm inpcb Ar addr
704 Show information on IP Control Block
711 Dump information about interrupt handlers.
714 .It Ic show Cm intrcnt
715 Dump the interrupt statistics.
719 Show interrupt lines and their respective kernel threads.
728 shows, also list kernel internal details.
732 Show information from the local APIC registers for this CPU.
735 .It Ic show Cm lock Ar addr
737 The output format is as follows:
738 .Bl -tag -width "flags"
741 Possible types include
749 Flags passed to the lock initialization function.
750 For exact possibilities see manual pages of possible lock types.
752 Current state of a lock.
761 .It Ic show Cm lockchain Ar addr
762 Show all threads a particular thread at address
764 is waiting on based on non-sleepable and non-spin locks.
767 .It Ic show Cm lockedbufs
768 Show the same information as "show buf", but for every locked
773 .It Ic show Cm lockedvnods
774 List all locked vnodes in the system.
778 Prints all locks that are currently acquired.
779 This command is only available if
781 is included in the kernel.
784 .It Ic show Cm locktree
787 .It Ic show Cm malloc
790 memory allocator statistics.
791 The output format is as follows:
793 .Bl -tag -compact -offset indent -width "Requests"
795 Specifies a type of memory.
796 It is the same as a description string used while defining the
797 given memory type with
798 .Xr MALLOC_DECLARE 9 .
800 Number of memory allocations of the given type, for which
802 has not been called yet.
804 Total memory consumed by the given allocation type.
806 Number of memory allocation requests for the given
810 The same information can be gathered in userspace with
814 .It Ic show Cm map Ns Oo Li / Ns Cm f Oc Ar addr
819 modifier is specified the
820 complete map is printed.
823 .It Ic show Cm msgbuf
824 Print the system's message buffer.
825 It is the same output as in the
828 It is useful if you got a kernel panic, attached a serial cable
829 to the machine and want to get the boot messages from before the
833 Displays short info about all currently mounted file systems.
835 .It Ic show Cm mount Ar addr
836 Displays details about the given mount point.
839 .It Ic show Cm object Ns Oo Li / Ns Cm f Oc Ar addr
840 Prints the VM object at
844 option is specified the
845 complete object is printed.
849 Print the panic message if set.
853 Show statistics on VM pages.
857 Show statistics on VM page queues.
860 .It Ic show Cm pciregs
861 Print PCI bus registers.
862 The same information can be gathered in userspace by running
863 .Dq Nm pciconf Fl lv .
867 Print current processor state.
868 The output format is as follows:
870 .Bl -tag -compact -offset indent -width "spin locks held:"
872 Processor identifier.
874 Thread pointer, process identifier and the name of the process.
876 Control block pointer.
882 CPU identifier coming from APIC.
885 .It Ic spin locks held
886 Names of spin locks held.
890 .It Ic show Cm pgrpdump
891 Dump process groups present within the system.
894 .It Ic show Cm proc Op Ar addr
897 is specified, print information about the current process.
898 Otherwise, show information about the process at address
902 .It Ic show Cm procvm
903 Show process virtual memory layout.
906 .It Ic show Cm protosw Ar addr
907 Print protocol switch structure
913 .It Ic show Cm registers Ns Op Li / Ns Cm u
914 Display the register set.
917 modifier is specified, it displays user registers instead of
918 kernel registers or the currently saved one.
923 modifier depends on the machine.
924 If not supported, incorrect information will be displayed.
927 .It Ic show Cm rman Ar addr
928 Show resource manager object
932 Addresses of particular pointers can be gathered with "show allrman"
937 Show real time clock value.
938 Useful for long debugging sessions.
941 .It Ic show Cm sleepchain
942 Show all the threads a particular thread is waiting on based on
946 .It Ic show Cm sleepq
947 .It Ic show Cm sleepqueue
948 Both commands provide the same functionality.
950 .Vt struct sleepqueue
952 Sleepqueues are used within the
954 kernel to implement sleepable
955 synchronization primitives (thread holding a lock might sleep or
956 be context switched), which at the time of writing are:
964 .It Ic show Cm sockbuf Ar addr
965 .It Ic show Cm socket Ar addr
972 Output consists of all values present in structures mentioned.
973 For exact interpretation and more details, visit
978 .It Ic show Cm sysregs
979 Show system registers (e.g.,
982 Not present on some platforms.
985 .It Ic show Cm tcpcb Ar addr
986 Print TCP control block
990 For exact interpretation of output, visit
995 .It Ic show Cm thread Op Ar addr
998 is specified, show detailed information about current thread.
999 Otherwise, information about thread at
1004 .It Ic show Cm threads
1005 Show all threads within the system.
1006 Output format is as follows:
1008 .Bl -tag -compact -offset indent -width "Second column"
1010 Thread identifier (TID)
1011 .It Ic Second column
1012 Thread structure address
1018 .It Ic show Cm tty Ar addr
1019 Display the contents of a TTY structure in a readable form.
1022 .It Ic show Cm turnstile Ar addr
1024 .Vt struct turnstile
1025 structure at address
1027 Turnstiles are structures used within the
1030 synchronization primitives which, while holding a specific type of lock, cannot
1031 sleep or context switch to another thread.
1032 Currently, those are:
1039 Show UMA allocator statistics.
1040 Output consists five columns:
1042 .Bl -tag -compact -offset indent -width "Requests"
1044 Name of the UMA zone.
1045 The same string that was passed to
1047 as a first argument.
1049 Size of a given memory object (slab).
1051 Number of slabs being currently used.
1053 Number of free slabs within the UMA zone.
1055 Number of allocations requests to the given zone.
1058 The very same information might be gathered in the userspace
1060 .Dq Nm vmstat Fl z .
1063 .It Ic show Cm unpcb Ar addr
1064 Shows UNIX domain socket private control block
1066 present at the address
1070 .It Ic show Cm vmochk
1071 Prints, whether the internal VM objects are in a map somewhere
1072 and none have zero ref counts.
1075 .It Ic show Cm vmopag
1076 This is supposed to show physical addresses consumed by a
1078 Currently, it is not possible to use this command when
1080 is compiled in the kernel.
1083 .It Ic show Cm vnode Op Ar addr
1088 For the exact interpretation of the output, look at the
1093 .It Ic show Cm vnodebufs Ar addr
1094 Shows clean/dirty buffer lists of the vnode located at
1098 .It Ic show Cm watches
1099 Displays all watchpoints.
1100 Shows watchpoints set with "watch" command.
1103 .It Ic show Cm witness
1104 Shows information about lock acquisition coming from the
1110 Toggles between remote GDB and DDB mode.
1111 In remote GDB mode, another machine is required that runs
1113 using the remote debug feature, with a connection to the serial
1114 console port on the target machine.
1115 Currently only available on the
1122 .It Ic kill Ar sig pid
1127 The signal is acted on upon returning from the debugger.
1128 This command can be used to kill a process causing resource contention
1129 in the case of a hung system.
1132 for a list of signals.
1133 Note that the arguments are reversed relative to
1136 .It Ic reboot Op Ar seconds
1137 .It Ic reset Op Ar seconds
1138 Hard reset the system.
1139 If the optional argument
1141 is given, the debugger will wait for this long, at most a week,
1145 Print a short summary of the available commands and command
1150 .It Ic capture reset
1151 .It Ic capture status
1153 supports a basic output capture facility, which can be used to retrieve the
1154 results of debugging commands from userpsace using
1157 enables output capture;
1161 will clear the capture buffer and disable capture.
1163 will report current buffer use, buffer size, and disposition of output
1166 Userspace processes may inspect and manage
1171 .Dv debug.ddb.capture.bufsize
1172 may be used to query or set the current capture buffer size.
1174 .Dv debug.ddb.capture.maxbufsize
1175 may be used to query the compile-time limit on the capture buffer size.
1177 .Dv debug.ddb.capture.bytes
1178 may be used to query the number of bytes of output currently in the capture
1181 .Dv debug.ddb.capture.data
1182 returns the contents of the buffer as a string to an appropriately privileged
1185 This facility is particularly useful in concert with the scripting and
1187 facilities, allowing scripted debugging output to be captured and
1188 committed to disk as part of a textdump for later analysis.
1189 The contents of the capture buffer may also be inspected in a kernel core dump
1197 Run, define, list, and delete scripts.
1200 section for more information on the scripting facility.
1202 .It Ic textdump dump
1204 .It Ic textdump status
1205 .It Ic textdump unset
1208 command to immediately perform a textdump.
1209 More information may be found in
1213 command may be used to force the next kernel core dump to be a textdump
1214 rather than a traditional memory dump or minidump.
1216 reports whether a textdump has been scheduled.
1218 cancels a request to perform a textdump as the next kernel core dump.
1221 The debugger accesses registers and variables as
1223 Register names are as in the
1224 .Dq Ic show Cm registers
1226 Some variables are suffixed with numbers, and may have some modifier
1227 following a colon immediately after the variable name.
1228 For example, register variables can have a
1230 modifier to indicate user register (e.g.,
1233 Built-in variables currently supported are:
1235 .Bl -tag -width ".Va tabstops" -compact
1237 Input and output radix.
1239 Addresses are printed as
1240 .Dq Ar symbol Ns Li + Ns Ar offset
1246 The width of the displayed line.
1248 The number of lines.
1249 It is used by the built-in pager.
1252 .It Va work Ns Ar xx
1255 can take values from 0 to 31.
1258 Most expression operators in C are supported except
1266 .Bl -tag -width ".No Identifiers"
1268 The name of a symbol is translated to the value of the symbol, which
1269 is the address of the corresponding object.
1273 can be used in the identifier.
1274 If supported by an object format dependent routine,
1276 .Oo Ar filename : Oc Ar func : lineno ,
1278 .Oo Ar filename : Oc Ns Ar variable ,
1280 .Oo Ar filename : Oc Ns Ar lineno
1281 can be accepted as a symbol.
1283 Radix is determined by the first two letters:
1289 decimal; otherwise, follow current radix.
1295 address of the start of the last line examined.
1300 this is only changed by
1306 last address explicitly specified.
1307 .It Li $ Ns Ar variable
1308 Translated to the value of the specified variable.
1309 It may be followed by a
1311 and modifiers as described above.
1312 .It Ar a Ns Li # Ns Ar b
1313 A binary operator which rounds up the left hand side to the next
1314 multiple of right hand side.
1317 It may be followed by a
1319 and modifiers as described above.
1323 supports a basic scripting facility to allow automating tasks or responses to
1325 Each script consists of a list of DDB commands to be executed sequentially,
1326 and is assigned a unique name.
1327 Certain script names have special meaning, and will be automatically run on
1330 events if scripts by those names have been defined.
1334 command may be used to define a script by name.
1335 Scripts consist of a series of
1337 commands separated with the
1341 .Bd -literal -offset indent
1342 script kdb.enter.panic=bt; show pcpu
1343 script lockinfo=show alllocks; show lockedvnods
1348 command lists currently defined scripts.
1352 command execute a script by name.
1354 .Bd -literal -offset indent
1360 command may be used to delete a script by name.
1362 .Bd -literal -offset indent
1363 unscript kdb.enter.panic
1366 These functions may also be performed from userspace using the
1370 Certain scripts are run automatically, if defined, for specific
1373 The follow scripts are run when various events occur:
1374 .Bl -tag -width kdb.enter.powerfail
1375 .It Dv kdb.enter.acpi
1376 The kernel debugger was entered as a result of an
1379 .It Dv kdb.enter.bootflags
1380 The kernel debugger was entered at boot as a result of the debugger boot
1382 .It Dv kdb.enter.break
1383 The kernel debugger was entered as a result of a serial or console break.
1384 .It Dv kdb.enter.cam
1385 The kernel debugger was entered as a result of a
1388 .It Dv kdb.enter.mac
1389 The kernel debugger was entered as a result of an assertion failure in the
1392 TrustedBSD MAC Framework.
1393 .It Dv kdb.enter.ndis
1394 The kernel debugger was entered as a result of an
1397 .It Dv kdb.enter.netgraph
1398 The kernel debugger was entered as a result of a
1401 .It Dv kdb.enter.panic
1404 .It Dv kdb.enter.powerfail
1405 The kernel debugger was entered as a result of a powerfail NMI on the sparc64
1407 .It Dv kdb.enter.powerpc
1408 The kernel debugger was entered as a result of an unimplemented interrupt
1409 type on the powerpc platform.
1410 .It Dv kdb.enter.sysctl
1411 The kernel debugger was entered as a result of the
1414 .It Dv kdb.enter.trapsig
1415 The kernel debugger was entered as a result of a trapsig event on the sparc64
1417 .It Dv kdb.enter.unionfs
1418 The kernel debugger was entered as a result of an assertion failure in the
1420 .It Dv kdb.enter.unknown
1421 The kernel debugger was entered, but no reason has been set.
1422 .It Dv kdb.enter.vfslock
1423 The kernel debugger was entered as a result of a VFS lock violation.
1424 .It Dv kdb.enter.watchdog
1425 The kernel debugger was entered as a result of a watchdog firing.
1426 .It Dv kdb.enter.witness
1427 The kernel debugger was entered as a result of a
1432 In the event that none of these scripts is found,
1434 will attempt to execute a default script:
1435 .Bl -tag -width kdb.enter.powerfail
1436 .It Dv kdb.enter.default
1437 The kernel debugger was entered, but a script exactly matching the reason for
1438 entering was not defined.
1439 This can be used as a catch-all to handle cases not specifically of interest;
1441 .Dv kdb.enter.witness
1442 might be defined to have special handling, and
1443 .Dv kdb.enter.default
1444 might be defined to simply panic and reboot.
1447 On machines with an ISA expansion bus, a simple NMI generation card can be
1448 constructed by connecting a push button between the A01 and B01 (CHCHK# and
1450 Momentarily shorting these two fingers together may cause the bridge chipset to
1451 generate an NMI, which causes the kernel to pass control to
1453 Some bridge chipsets do not generate a NMI on CHCHK#, so your mileage may vary.
1454 The NMI allows one to break into the debugger on a wedged machine to
1456 Other bus' bridge chipsets may be able to generate NMI using bus specific
1459 Header files mention in this manual page can be found below
1469 .Pa netinet/in_pcb.h
1491 debugger was developed for Mach, and ported to
1493 This manual page translated from
1496 .An Garrett Wollman .
1498 .An Robert N. M. Watson